TABLE 2.
Publication year of the 100 top-cited studies.
| Year | Number of studies | Total citation | Average citation |
| 1967 | 1 | 910 | 910 |
| 1968 | 2 | 1,979 | 990 |
| 1971 | 1 | 24,252 | 24,252 |
| 1976 | 1 | 933 | 933 |
| 1982 | 1 | 936 | 936 |
| 1987 | 1 | 1,201 | 1,201 |
| 1989 | 1 | 2,635 | 2,635 |
| 1990 | 2 | 1,646 | 823 |
| 1991 | 5 | 8,262 | 1,652 |
| 1992 | 4 | 7,775 | 1,944 |
| 1993 | 3 | 10,737 | 3,579 |
| 1994 | 2 | 4,149 | 2,075 |
| 1995 | 2 | 1,912 | 956 |
| 1996 | 3 | 2,587 | 862 |
| 1997 | 4 | 7,117 | 1,779 |
| 1998 | 6 | 8,561 | 1,427 |
| 1999 | 8 | 8,353 | 1,044 |
| 2000 | 5 | 8,269 | 1,654 |
| 2001 | 6 | 7,795 | 1,299 |
| 2002 | 6 | 8,704 | 1,451 |
| 2003 | 6 | 9,136 | 1,523 |
| 2004 | 7 | 7,168 | 1,024 |
| 2006 | 4 | 3,349 | 837 |
| 2007 | 6 | 7,530 | 1,255 |
| 2008 | 2 | 1,716 | 858 |
| 2009 | 1 | 1,242 | 1,242 |
| 2010 | 1 | 1,212 | 1,212 |
| 2011 | 5 | 12,642 | 2,528 |
| 2012 | 1 | 947 | 947 |
| 2013 | 2 | 1,698 | 849 |
| 2014 | 1 | 770 | 770 |