birthweight numBirths numSurvived
1              13            0
1.5             8            0
2              20            1
2.5            15            2
3              39           10
3.5            46           26
4              60           46
4.5            99           81
5             170          154
5.5           360          332
6             721          705
6.5          1002          977
7            1403         1362
7.5          1141         1115
8             942          924
8.5           459          443
9             301          297
9.5           132          127
10             63           57
10.5           25           23
11             15           13
11.5            2            2
12              0            0
12.5            0            0
13              1            0