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         1868        682 
1995         3324       1156 
1996         3559       1250 
1997         2312        789 
1998        23170       9773 
1999        14478       5551 
2000        40121      16638 
2001        40970      15967 
2002        32090      14355 
2003        60249      25009 
2004        47516      18226 
2005        83688      25744 
2006       108178      34636 
2007       198977      61217 
2008       120428      34335 
2009        98668      27762 
2010       113928      31711 
2011       168987      46786 
2012       158773      43943 
2013       237923      67644 
2014       580813     149176 
2015       702769     186373 
2016       676851     175750 
2017       575913     155730 
2018       376015     105469 
2019       902056     220657 
2020       651738     166322 
2021       870619     207578 
2022       645239     184735 
2023       592393     169556 
2024       374287     108752