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         2189        792 
1995         3357       1167 
1996         3570       1254 
1997         2326        793 
1998        23226       9794 
1999        14498       5559 
2000        40369      16749 
2001        42874      16623 
2002        32384      14478 
2003        60888      25255 
2004        47771      18325 
2005        84541      26000 
2006       109712      35080 
2007       202038      62032 
2008       123186      35083 
2009       100076      28145 
2010       116406      32363 
2011       173585      48029 
2012       161470      44685 
2013       246793      70057 
2014       588002     151056 
2015       713102     189227 
2016       686260     178090 
2017       581280     157318 
2018       384615     107850 
2019       913285     224124 
2020       675786     173023 
2021       888140     212385 
2022       660146     188800 
2023       606821     172850 
2024       268885      77945