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         1356        504 
1994         1752        642 
1995         3315       1153 
1996         3392       1193 
1997         2291        783 
1998        23130       9757 
1999        14444       5537 
2000        40047      16606 
2001        40902      15935 
2002        32138      14362 
2003        60051      24936 
2004        47422      18193 
2005        83362      25646 
2006       107640      34478 
2007       197788      60897 
2008       119259      34020 
2009        97993      27581 
2010       112983      31465 
2011       167344      46344 
2012       157773      43684 
2013       234758      66781 
2014       577099     147248 
2015       697869     184187 
2016       673420     174375 
2017       575046     155301 
2018       371919     104355 
2019       896989     219277 
2020       648259     165342 
2021       867368     206780 
2022       642750     184022 
2023       586339     167856 
2024       462128     134500