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         2051        745 
1995         3339       1161 
1996         3562       1251 
1997         2320        791 
1998        23173       9774 
1999        14481       5552 
2000        40142      16648 
2001        45897      17609 
2002        32140      14375 
2003        60373      25058 
2004        47560      18242 
2005        83863      25797 
2006       108527      34739 
2007       199606      61384 
2008       121100      34516 
2009        98921      27830 
2010       114448      31849 
2011       169706      46983 
2012       159454      44132 
2013       239635      68102 
2014       582180     149529 
2015       704685     186910 
2016       677845     176033 
2017       576780     155974 
2018       377615     105918 
2019       904313     221289 
2020       653602     166864 
2021       871915     207917 
2022       646552     185119 
2023       595262     170177 
2024       372322     108260