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          503        190 
1992          936        367 
1993         1669        610 
1994         2326        839 
1995         3571       1239 
1996         3576       1256 
1997         2332        795 
1998        23269       9811 
1999        14531       5572 
2000        40486      16801 
2001        43077      16704 
2002        32540      14546 
2003        61305      25414 
2004        48037      18424 
2005        85595      26313 
2006       111002      35466 
2007       204523      62707 
2008       125639      35750 
2009       102211      28721 
2010       118773      32983 
2011       178202      49282 
2012       165423      45755 
2013       255839      72559 
2014       640803     162895 
2015       743814     196750 
2016       571802     152512 
2017       608808     163358 
2018       409339     113086 
2019       941271     230432 
2020       690865     177137 
2021       897899     215003 
2022       666771     190727 
2023       605955     174465 
2024       205702      59218