:;<=>?>;<@;A@BC?>CD=>EFG@>?H;AGFI>@?FGF=
C<=C:?JCDB;BJDC?>;<@C?C D;:CDDFEFD><B;DC<=
KLM NOKPN
QRSTU VW
T XYTZ[\ ]
^
U _
] U`
_
UXabc d V
Tc eTT`cSTfUfg [\cbU`
a T \ W
gXTZ V
d
]\cThUXd
U _
X Th b W
cX \cbU`
_
UX
f T Xa \`T`c
X T W
bZT`] T\`Z
cST\ ]cg\[fUfg [\cbU`
b W
U`
cST
U`T
S\`Z\] U`
W
TigT`] TU _
cST[b abc\cbU`
W
] U``T]cTZebcS
fg V
[b]
W
c\cb W
cb]
W
\`ZU`
cSTUcST X
bc
b W
cST
X T W
g [c
U _
b`]XT \ W
b `h
cTaf UX \Xd W
f\cb\[
aU V
b [ bcd jkT W
bZT cST
W
]\[TU _
cSb W
fST`Ua l
T`U`m bc
WW
f\cb\[
Z ba T`
W
bU`b W
f\Xcb]g [\X[d W
bh `b _
b] \`c
\ W
m
cUhTcST XebcS
U __
b] b\[
W
c\cb W
cb]
W
] U`] TX`b `h
f Ufg [ \cbU`
b ` _
[Ue
\`Z Ugc
_
[Uembc
ZT _
b `T W
cST
XT \[
b `cT`
W
bc d
\`Z
ZbX T]cbU`
W
U _
abh X \cbU`j
RST V
\ W
b]U Vn
T]cbYT
U _
cSb WW
cgZde\
W
cU
To\ab `T cST
W
]\[T\`Z
] U`ZbcbU`
W
]U``T ]cTZ
ebcScST W
S \fb `hU _W
f\cb \[
ZbYT X W
bcbT WV
TceTT`cST W
b p TU _
X Thb W
cT X T Z
\`Z
\ ]cg \[
f Ufg [ \l
cbU`
W
j
RST
\`\[d W
b W
e\
W
] U`Zg]cT Z
m\ V
UYT\[ [mb `
X T[\cbU` cU
T] U`Uab]
_
\ ]cUX W
]XT \cb`h
cST W
TZb __
T XT`] T W
j
RST
\`\[d W
b W
e\
W
] \XXbTZ Ugc
b `
X T[\cbU`cUcSTg `bc W
U _q rst
[TYT[b `
u
U[\`Zj
RST
] U`Zg]cT Z \`\[d W
b W
b `Z b]\cT Z cS\c
T ] U`Uab] \`Z
T Zg] \cbU`lXT[ \cTZ ] U`ZbcbU`
W
f[ \dTZ
\`
baf UXc\`c
X U[Tb`
cST W
S\fb `hU _
cTa f UX \Xd
X Thb W
cT X T ZabhX \cbU`j
RSb W
\[
W
U]U`l
_
bXa TZ cST
Tob W
cT`]T
U _
\[ b `
^V
Tc eT T `cTa f UX \Xd
X Th b W
cT XTZabhX \cbU`
\`ZSg a \`
]\ fbc\[
\ W
eT[ [
\ W
cST
[TYT[U _
T]U`Uab]
ZTYT[Ufa T`c
U _
f\Xcb]g [ \X
X ThbU`
W
jvf\cb\[
W
cXg]cgXT
U _
cTaf UX \Xd
X Th b W
cT X T ZabhX \cbU`e\
WW
bab [ \X cU
`U`lX Th b W
cTX TZabhX \cbU`
W
cXg]cgXTj
RSg W
m
bca \d
ST[fZT _
b`ThT`T X \[
Z bX T]cbU`
W
U _
b`
_
UXa \[
f Ufg [ \cbU`abhX \cbU`j
wxyz{O|M
Qf Ufg [ \ c
bU`m W
f\
c
b \[ZbYTX W
b c d
m[U ]\[[TYT[m u
U[\`Z j
}~NO {| PN}{~
!
"
#$%#&'() *+,*-./,(.0'1
2
"
34
52
"
3
46
7
4889
4
8 :;
<
=
"
!
>
?
5@AB
3
C >
@3
>
6
4
5
>
A
=DEF
488 :6
<
5
6
4
! "
#
$
"
%
"&'
!"
"
"
"
(
"
&"
)
%
" '"
#
"
( *
&
(
'
+
,#
"
#
!
(
"
"
%
&
"
( (
""
"
"
#
"
"&'
!
(
"-. (
"
"
&
"
#
"
'
#
(
"
%##
)
/0
)
1
$2 3456
7
2 6
)
8
)
!
%
&
(
"'
#
"
%
'"&
"
"
"
"
$
*6
9"
#
"
" )
(
"
$
&"
#
"
&"
$
"
"
" ,
!
%
&
#
!
"
$
:6
9"&
#
!
"9
"
$
56
"
"
"
"9"
'
!
% %
"
"
;
$
"
"
"
"
+
&
"
"
$<
9"
#
"
(
"
#
"
"
% #
!
( #
"
"
"-
. (
"
,
9"
+
&"
"
,
&'
"
( (
"'
,#
"&
"
"
)
(
!
(
"
% %
""
"
(
"
=
"
%, (
"
"
""
#
"
(
"
%#
+
#
)
%
7
>
(
"&
9"
!
%
"
(
""&"
"
"
% (
"
"
%%
""
"
$
>
&&
'
"
% % # % #%## (
" "
,#
$
"
'"
##
!
) (
"
&
$
>
"
)
8/?
)
=
$
*@@@6
-
.
"
&
,
"
%
'
#
"
)""
" "
%%
""
"
(
"
&
,
"
%
"
""
(
"
#
'
'
#
-. (
"!&
#
!
"
"
(
" "
# % (
" A
# B
'
# C
"
/
A
)! D'
B
)
=
"
(
! 6
) (( (
)"
(
""
# #
"
%
'
' #
&
(
"
&"
% (
"
"
/ E
#
"
=
! F
8
$
*@@5
$
*@@5,
$
*@@G6
-H
'
"
$
(
"
"
""
(
"
+
"I "
"
%
"
#
%
"
&
$ , (
"
""
+
"
"" -
. (
"&
&'
#
"
"
(
"
,
"9"
%%
""
"
)
'
#
!"
,
!
+
"
""
"
#
&
/ E
#
"
=
! F
8
$
*@@G6
-. (
"&
% % (
!
$
&"
" ,
"
%
"
$
"
"
"
""
"&'
!&
-
. (
"
!
% (
"
#
"
"
#
""&
9" ! ( (
$ (
)"9"
$
(
""
% #
!
%
!
&
#
!
"
-. (
"
"
#
&
''
#
!
(
"
"
%
"
#
!
(
"
%
"
""
"&'
!"
"
"
$
-"-
#
"
( *
&
(
-H
"
"
!
$ (
)"9"
$
"
(
"&
&'
+
"
" &
(
" "&"
"
"
%
'
#
9"
"
% (
"
#
!
"
%%
""
"
-
JKLMKNONPQKRPOLMKSTSULV W STPV KN
. (
"
#
!
%%
(
'
(
"
% %
""
"
,
"
)" "
(
""
"" '
' #
+
(
"
#
'
' #
&
! ,
"
" 9
"
%
&'
"
'
% (
%%
""
"
%
&
#
"
#
"
#
$
-"-)
8
$
"
$
&
#
+
!
"9
"
$
!
'
$
"
-
!
"
!
#
$
"
$%
&
'
'
(
$%
'
'
)
$
*
&
)
'
'
'
$ +
(
,
' ,
$
! -.
'
/
0
$$$
(
"
$
'
$1
2
)
'!
"
&
$
3 4
5676 89: ;
<=>? @<>=
9A; B:
>
;
<@
9
@><
;:
4
9C9DE
??
E 5 4=
: E
?
E F@
9
@><
; : 4
9C 4
CG9
<4=H
B9I I
>
CE
=
J
E: KE EC 7
LLMNOPPQ
RST
UVWX YZ[\]^_`]ab`[ZcdeY`fc]bcY[Yg^]h[\fifb[^Yjk[Y[l`[lmYjngglmfopqkr
150 160 170 180 190 200 210 220 230 240
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
Thousand .
![Contents [e-Informatica Software Engineering Journal, Vol. 5, 2011, Issue 1]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==)