TABLE 1.
Number of Participants at Risk for Each Year of the Study by Age Group
| Season | Age Group, y | Total | |||||||
|---|---|---|---|---|---|---|---|---|---|
| <9 | <10 | <11 | <12 | <13 | <14 | <15 | <16 | ||
| 1 (as of May 1, 2001) | 274 | 290 | 323 | 331 | 357 | 413 | 326 | 323 | 2637 |
| 2 (as of May 1, 2002) | 265 | 298 | 300 | 353 | 321 | 397 | 305 | 336 | 2575 |
| 3 (as of May 1, 2003) | 267 | 297 | 316 | 313 | 333 | 362 | 272 | 304 | 2464 |
| 4 (as of May 1, 2004) | 274 | 298 | 306 | 320 | 309 | 339 | 269 | 237 | 2352 |
| 5 (as of May 1, 2005) | 249 | 273 | 299 | 330 | 309 | 329 | 257 | 232 | 2278 |
| Total | 1329 | 1456 | 1544 | 1647 | 1629 | 1840 | 1429 | 1432 | 12,306 |
| Mean (standard deviation) | 266 (10) | 291 (11) | 309 (10) | 329 (15) | 326 (20) | 308 (36) | 286 (29) | 286 (49) | |