Thyroid cancer incidence rate in Tianjin during recent 21 years(l/100,000).
| Year | Caese | Crude rates | World standard rates |
|---|---|---|---|
| 1981 | 30 | 0.869 | 0.804 |
| 1982 | 47 | 1.503 | 1.317 |
| 1983 | 46 | 1.444 | 1.506 |
| 1984 | 39 | 1.201 | 1.079 |
| 1985 | 54 | 1.617 | 1.354 |
| 1986 | 48 | 1.413 | 1.310 |
| 1987 | 57 | 1.653 | 1.447 |
| 1988 | 49 | 1.400 | 1.190 |
| 1989 | 68 | 1.914 | 1.496 |
| 1990 | 71 | 1.971 | 1.681 |
| 1991 | 69 | 1.904 | 1.627 |
| 1992 | 56 | 1.537 | 1.279 |
| 1993 | 64 | 1.745 | 1.415 |
| 1994 | 58 | 1.576 | 1.186 |
| 1995 | 75 | 2.034 | 1.514 |
| 1996 | 59 | 1.598 | 1.185 |
| 1997 | 80 | 2.167 | 1.644 |
| 1998 | 86 | 2.314 | 1.734 |
| 1999 | 74 | 1.988 | 1.468 |
| 2000 | 93 | 2.485 | 1.825 |
| 2001 | 95 | 2.543 | 1.799 |
| Total | 1318 | 1.770 | 1.422 |
Comparison of the thyroid cancer incidence rate every year from 1981 to 2001 using the χ2 trend test method, χ2=48.794, P=0.000.This difference has statistical significance.