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          492        186 
1992          770        310 
1993         1356        504 
1994         1916        698 
1995         3330       1158 
1996         3562       1251 
1997         2315        790 
1998        23173       9774 
1999        14481       5552 
2000        40127      16641 
2001        45268      17400 
2002        32114      14365 
2003        60307      25032 
2004        47537      18234 
2005        83800      25778 
2006       108367      34692 
2007       199441      61340 
2008       120731      34416 
2009        98804      27798 
2010       114238      31793 
2011       169418      46905 
2012       159193      44052 
2013       238893      67899 
2014       581520     149356 
2015       703869     186675 
2016       677770     175991 
2017       576405     155872 
2018       377313     105821 
2019       903743     221098 
2020       652821     166649 
2021       871376     207782 
2022       645974     184951 
2023       594140     169890 
2024       370027     107590