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         2078        754 
1995         3345       1163 
1996         3562       1251 
1997         2320        791 
1998        23173       9774 
1999        14481       5552 
2000        40149      16651 
2001        41807      16247 
2002        32152      14380 
2003        60395      25066 
2004        47572      18246 
2005        83897      25807 
2006       108580      34754 
2007       199697      61408 
2008       121203      34543 
2009        98982      27848 
2010       114573      31883 
2011       169904      47036 
2012       159525      44151 
2013       239978      68196 
2014       582674     149655 
2015       705103     187027 
2016       677891     176045 
2017       577182     156083 
2018       377806     105972 
2019       904561     221383 
2020       653840     166960 
2021       872213     207983 
2022       654097     187082 
2023       598840     171182 
2024       372797     108399