|
Year of operation |
Valve type |
Total |
|||
|
Mechanical |
|
||||
|
1986 |
2794 |
53.84% |
2395 |
46.16% |
5189 |
|
1987 |
3122 |
62.64% |
1862 |
37.36% |
4984 |
|
1988 |
3466 |
67.91% |
1628 |
32.09% |
5074 |
|
1989 |
3484 |
71.09% |
1417 |
28.91% |
4901 |
|
1990 |
3814 |
75.33% |
1249 |
24.67% |
5063 |
|
1991 |
3730 |
72.92% |
1385 |
27.08% |
5115 |
|
1992 |
3973 |
74.21% |
1381 |
25.79% |
5354 |
|
1993 |
3951 |
72.72% |
1482 |
27.28% |
5433 |
|
1994 |
4398 |
73.47% |
1588 |
26.53% |
5986 |
|
1995 |
3911 |
70.60% |
1629 |
29.40% |
5540 |