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          532        200 
1992          936        367 
1993         1669        610 
1994         2333        842 
1995         4430       1529 
1996         3602       1265 
1997         2340        798 
1998        23334       9837 
1999        14624       5612 
2000        40751      16923 
2001        41820      16315 
2002        32994      14731 
2003        62036      25712 
2004        48718      18693 
2005        87119      26753 
2006       112868      36012 
2007       207844      63615 
2008       128869      36618 
2009       104702      29396 
2010       121698      33755 
2011       183431      50709 
2012       169996      47024 
2013       265263      75218 
2014       661296     168621 
2015       773725     204999 
2016       576920     154205 
2017       585936     157528 
2018       406866     114141 
2019       925416     226010 
2020       713367     183116 
2021       926781     222929 
2022       693430     198244 
2023       630996     181557 
2024        72645      21065