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          468        178 
1992          743        301 
1993         1308        487 
1994         1675        615 
1995         3048       1064 
1996         2977       1052 
1997         1858        641 
1998        21674       9215 
1999        13395       5144 
2000        38597      15959 
2001        39425      15313 
2002        33286      14633 
2003        57736      24022 
2004        46288      17758 
2005        81370      25049 
2006       105008      33705 
2007       191745      59270 
2008       112211      32132 
2009        93059      26230 
2010       145477      39081 
2011       157841      43783 
2012       149065      41303 
2013       220967      62952 
2014       564929     143942 
2015       798351     210165 
2016       658846     171216 
2017       554493     150086 
2018       351465      98736 
2019       863239     210730 
2020       616660     156941 
2021       829528     196979 
2022       619659     177371 
2023       558617     159804 
2024       617601     177973 
2025       220700      63094