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          492        186 
1992          770        310 
1993         1359        505 
1994         2317        836 
1995         3365       1170 
1996         3576       1256 
1997         2326        793 
1998        23242       9800 
1999        14517       5566 
2000        40428      16774 
2001        42988      16670 
2002        32431      14496 
2003        61070      25323 
2004        47878      18365 
2005        85069      26156 
2006       110502      35313 
2007       203387      62399 
2008       124619      35476 
2009       101155      28434 
2010       117776      32721 
2011       176327      48764 
2012       163925      45328 
2013       253703      71767 
2014       603828     154601 
2015       728849     193279 
2016       716843     185138 
2017       600247     161973 
2018       395201     110739 
2019       929439     228204 
2020       699745     178561 
2021       892149     213506 
2022       662532     189489 
2023       600997     173045 
2024       251565      72890