Year Observations     Objects
1950            2          1 
1951            6          3 
1953           14          8 
1954           12          5 
1955           12          6 
1956            8          4 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978           12          5 
1981           18          5 
1982           13          7 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990          213         76 
1991          856        306 
1992          653        269 
1993         1176        442 
1994         1481        553 
1995         2350        830 
1996         2614        928 
1997         2477        846 
1998        23902       8540 
1999        12798       4882 
2000        36238      14879 
2001        41352      16236 
2002        34882      14925 
2003        56773      23260 
2004        44731      17036 
2005       302366     136292 
2006       330080     147427 
2007       191397      59314 
2008       107298      30623 
2009        87626      24529 
2010       135417      36077 
2011       142122      38676 
2012       169771      36783 
2013       223397      56188 
2014       469908     116614 
2015       708020     185185 
2016       598335     154635 
2017       502343     136567 
2018       300065      84865 
2019       801018     196196 
2020       524614     132934 
2021       705724     165118 
2022       548456     157334 
2023       508141     145590 
2024       548050     157539 
2025       522089     148497 
2026       367993      87491