Year Observations     Objects
1950            2          1 
1951            6          3 
1953            4          2 
1954            2          1 
1955            4          2 
1956            2          1 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978            8          3 
1981            4          2 
1982           12          6 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990           32         14 
1991          503        190 
1992          936        367 
1993         1669        610 
1994         2329        840 
1995         3796       1315 
1996         3578       1257 
1997         2335        796 
1998        23277       9814 
1999        14542       5577 
2000        40516      16814 
2001        43117      16723 
2002        32587      14568 
2003        61401      25453 
2004        48134      18463 
2005        85818      26376 
2006       111229      35531 
2007       205022      62839 
2008       126094      35872 
2009       102650      28837 
2010       119188      33090 
2011       178940      49483 
2012       166102      45962 
2013       257261      72972 
2014       643075     163538 
2015       744183     197476 
2016       572958     152889 
2017       611096     163878 
2018       404252     113315 
2019       941659     230417 
2020       693896     177968 
2021       901146     215823 
2022       669086     191369 
2023       609845     175529 
2024       200243      57599