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          512        193 
1992          936        367 
1993         1669        610 
1994         2329        840 
1995         4163       1438 
1996         3584       1259 
1997         2334        796 
1998        23296       9821 
1999        14569       5588 
2000        40607      16857 
2001        41618      16230 
2002        32697      14616 
2003        61647      25549 
2004        48381      18560 
2005        86273      26511 
2006       111794      35699 
2007       206067      63129 
2008       126997      36116 
2009       103426      29050 
2010       120009      33305 
2011       180455      49894 
2012       167610      46375 
2013       260011      73750 
2014       645669     164677 
2015       749905     199032 
2016       576319     153833 
2017       611315     163579 
2018       406951     114034 
2019       930917     227051 
2020       698232     179254 
2021       906858     217495 
2022       676737     193590 
2023       614871     176988 
2024       151026      43191