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         3706       1284 
1996         3578       1257 
1997         2335        796 
1998        23274       9813 
1999        14535       5574 
2000        40499      16806 
2001        43086      16708 
2002        32552      14552 
2003        61330      25424 
2004        48063      18435 
2005        85640      26327 
2006       111076      35487 
2007       204684      62750 
2008       125793      35791 
2009       102370      28763 
2010       118916      33019 
2011       178431      49344 
2012       166190      45858 
2013       258700      72931 
2014       643833     163349 
2015       744375     196941 
2016       572367     152686 
2017       610206     163631 
2018       404313     112783 
2019       942543     230752 
2020       691865     177398 
2021       898850     215259 
2022       667517     190938 
2023       606767     174697 
2024       199185      57302