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         2258        815 
1995         3362       1169 
1996         3570       1254 
1997         2326        793 
1998        23234       9797 
1999        14506       5562 
2000        40399      16762 
2001        42944      16651 
2002        32415      14489 
2003        60996      25296 
2004        47840      18351 
2005        84845      26089 
2006       110172      35214 
2007       202890      62266 
2008       124173      35354 
2009       100761      28328 
2010       117359      32614 
2011       175466      48531 
2012       163376      45179 
2013       251890      71273 
2014       597799     153199 
2015       723738     192001 
2016       708219     183246 
2017       598380     161503 
2018       393295     110221 
2019       926629     227470 
2020       678802     173826 
2021       890836     213136 
2022       661525     189190 
2023       614867     174118 
2024       268288      77784