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         3793       1314 
1996         3578       1257 
1997         2335        796 
1998        23274       9813 
1999        14542       5577 
2000        40514      16813 
2001        43115      16722 
2002        32587      14568 
2003        61395      25450 
2004        48128      18460 
2005        85800      26371 
2006       111219      35528 
2007       205006      62835 
2008       126083      35869 
2009       102626      28831 
2010       119160      33083 
2011       178920      49478 
2012       166049      45947 
2013       257188      72959 
2014       642830     163500 
2015       743912     197411 
2016       572929     152884 
2017       611159     163884 
2018       404205     113303 
2019       941833     230463 
2020       693761     177930 
2021       901097     215808 
2022       668964     191335 
2023       609674     175484 
2024       200013      57535