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         2258        815 
1995         3362       1169 
1996         3573       1255 
1997         2326        793 
1998        23237       9798 
1999        14511       5564 
2000        40404      16764 
2001        42963      16660 
2002        32424      14493 
2003        61039      25311 
2004        47840      18351 
2005        84894      26105 
2006       110343      35266 
2007       203103      62322 
2008       124385      35410 
2009       100932      28373 
2010       117518      32655 
2011       175878      48642 
2012       163598      45241 
2013       252841      71529 
2014       602834     154353 
2015       727690     192961 
2016       711548     184011 
2017       599383     161775 
2018       394472     110544 
2019       928792     228047 
2020       686206     175562 
2021       891499     213322 
2022       662046     189345 
2023       599609     172653 
2024       259837      75287