WTA排名中的积分是怎么算来的，是几年的累加值吗？有年数限制吗？

下面是WTA积分方法：
SINGLES and DOUBLES ROUND POINTS
--- Description --- W F SF QF R16 R32 R64 R128 QLFR Q3 Q2 Q1
Grand Slam (Singles) 700 492 314 174 96 62 38 2 31 25 15 2
Grand Slam (Doubles) 700 492 314 174 96 62 2 - 24 - - -
Tour Championships 525 369 235 130 72 - - - - - - -
Tier I (128) $3,000,000 350 246 157 87 48 31 19 1 15.5 - 7.5 1
Tier I (32) $3,000,000 350 246 157 87 48 1 - - 21.5 - - -
Tier I (128) $2,000,000 325 228 146 81 45 28 16 1 11 - 6.25 1
Tier I (32) $2,000,000 325 228 146 81 45 1 - - 20 - - -
Tier I (64) $1,340,000 300 210 135 75 42 25 1 - 10.5 - 5.75 1
Tier I (32) $1,340,000 300 210 135 75 42 1 - - 18.5 10.5 5.75 1
Tier I (16) $1,340,000 300 210 135 75 1 - - - 19 - - -
Tier II (32) $650,000 220 154 99 55 29 1 - - 13.25 7.75 4.5 1
Tier II (16) $650,000 220 154 99 55 1 - - - 13 - - -
Tier II (64) $600,000 195 137 88 49 25 14 1 - 6.75 - 4 1
Tier II (32) $600,000 195 137 88 49 25 1 - - 11.75 6