我有以下数据集：

structure(list(...1 = c("Catalunya", "PIB", "Demanda interna1", 
"Demanda externa1", "Espanya", "PIB", "Demanda interna1", "Demanda externa1", 
"Zona euro", "PIB", "Demanda interna1", "Demanda externa1", "PIB d'Alemanya", 
"PIB de França", "PIB d'Itàlia", "Internacional", "PIB de la UE-27", 
"PIB dels EUA", "PIB del Japó"), `2020` = c(NA, -11.9, -7.4, 
-4.5, NA, -11.2, -9, -2.2, NA, -6.1, -5.57, -0.53, -3.8, -7.5, 
-9, NA, -5.6, -2.2, -4.3), `2021` = c(NA, 6.2, 3.8, 2.4, NA, 
6.4, 5.9, 0.5, NA, 5.6, 4.24, 1.36, 3.2, 6.4, 8.3, NA, 5.7, 5.8, 
2.1), `2022` = c(NA, 5.5, 2.7, 2.8, NA, 5.5, 5.12183164381576, 
0.378168356184236, NA, 3.6, 3.76, -0.16, 1.8, 2.5, 3.7, NA, 3.5, 
1.9, 1.1), `1r 2023` = c(NA, 3.2, 1.1, 2.1, NA, 4.1, 1.3, 2.8, 
NA, 1.2, 0.63, 0.57, -0.2, 1, 2.1, NA, 1.1, 1.71772942152937, 
2), `2n 2023` = c(NA, 2.1, 1.2, 0.9, NA, 2, 2.2, -0.2, NA, 0.5, 
0.46, 0.04, 0.1, 1.1, 0.3, NA, 0.4, 2.38237207285343, 1.7), `3r 2023` = c(NA, 
2.1, NA, NA, NA, 1.8, 1.6, 0.2, NA, 0.1, NA, NA, -0.4, 0.7, 0, 
NA, 0.1, 3, 1.2)), row.names = c(NA, -19L), class = c("tbl_df", 
"tbl", "data.frame"))

字符串
我在Markdown中创建了一个表格（到PDF），使用以下代码：

options(knitr.kable.NA = "-")

grp_nm <- c("Catalunya", "Espanya", "Zona euro", "Internacional")

p3_1 <- 
  p3_1 |> 
  mutate(grp = ifelse(...1 %in% grp_nm, ...1, NA),
         ...1 = case_when(str_detect(...1, "interna1") ~ "$\\text{Demanda interna}^1$",
                          str_detect(...1, "externa1") ~ "$\\text{Demanda externa}^1$",
                          TRUE ~ ...1))|>
  fill(grp) |> 
  filter(!...1 %in% grp_nm) |> 
  select(grp, everything())
  

kable(p3_1[, -1],
      align = "lrrrrrr",
      col.names = c("", names(p3_1[-(1:2)])),
      booktabs=TRUE,
      digits=1,
      format.args = list(big.mark="."),
      linesep = "" ,
      caption="Producte interior brut (\\% de variació interanual, llevat dels casos indicats)", escape = FALSE) |>
  add_header_above(c("", "Any" = 3, "Trimestre" = 3), bold=T) |>
  kable_styling(latex_options=c("HOLD_position","scale_down"), position="center") |> 
  column_spec(1, bold=T, width="4cm") |> 
  column_spec(2:7, width="2cm") |> 
  row_spec(0, bold = T) |> 
  pack_rows(index = table(p3_1$grp), background="lightgray") |>
  footnote(general="Idescat; Eurostat; INE; BEA; ESRI; Agència Estatal d'Administració Tributària.", general_title = "Font:", footnote_as_chunk = T,)  |>
  footnote(general="$^{A}$Dada avançada. $^{1}$Contribució al creixement. $^{2}$Sèrie original corregida d'efectes de calendari.
           $^{3}$En valors constants. Exclou estacions de servei.",  escape = F, general_title = "Nota:", threeparttable = TRUE, footnote_as_chunk = T,)

型
输出如下：

的数据
如何更改灰色线条的背景色，使第一行和标题之间没有空格？