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          532        200 
1992          936        367 
1993         1669        610 
1994         2333        842 
1995         4425       1527 
1996         3602       1265 
1997         2340        798 
1998        23330       9835 
1999        14615       5608 
2000        40721      16911 
2001        41793      16303 
2002        32930      14708 
2003        61949      25676 
2004        48644      18666 
2005        86952      26707 
2006       112635      35946 
2007       207588      63545 
2008       128489      36515 
2009       104486      29338 
2010       121420      33681 
2011       182991      50588 
2012       169694      46941 
2013       264597      75032 
2014       660291     168352 
2015       772599     204699 
2016       578249     154297 
2017       590532     158054 
2018       406574     114061 
2019       929447     226858 
2020       712167     182786 
2021       924421     222328 
2022       691450     197695 
2023       625774     180079 
2024       102326      29619